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Flu Complications

Worried about flu complications? Even for a healthy person, the flu can put you out of commission for days -- even weeks. And there's always the chance that the flu can cause more serious health problems or flu complications such as sinusitis (sinus infections), bronchitis, or even pneumonia.

According to the CDC, 5% to 20% of the U.S. population contracts the flu annually. More than 200,000 of those individuals are hospitalized for flu complications, and approximately 3,000 to 49,000 people die of flu-related problems.

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What Is the Flu?

Influenza -- commonly shortened to "flu" -- is an extremely contagious viral disease that appears most frequently in the fall and winter. The flu comes on fast and strong, spreading through your upper respiratory tract and sometimes invading your lungs.

What Are the Symptoms of the Flu?

With the flu, you may have the following symptoms:

  • Fever (usually high)
  • Headache
  • Tiredness (can be extreme)
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Body aches
  • Diarrhea and vomiting (more common among children than adults)

(For more information about flu symptoms, see WebMD's Flu Symptoms: What You Might Feel.)

What Are Common Flu Complications?

The most common flu complications include viral or bacterial pneumonia, muscle inflammation (myositis), central nervous system disease, and heart problems including heart attacks, inflammation of the heart muscle (myocarditis), and inflammation of the sac around the heart (pericarditis).

Other flu complications may include ear infections and sinus infections, especially in children, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

Those at highest risk for flu complications include adults over 50, children ages 6 months to 4 years, nursing home residents, adults and children with heart or lung disease, people with compromised immune systems (including people with HIV/AIDS), and pregnant women.

(For in-depth information, see WebMD's Flu and Chronic Medical Conditions.)

Is Pneumonia a Serious Flu Complication?

Yes, pneumonia is a common and very serious flu complication. Pneumonia can occur from direct involvement of the flu virus in the lung or when a bacterial infection develops during the course of the flu. Whether viral or bacterial, pneumonia can make you quite ill and may require hospitalization.

With pneumonia, you may have chills, fever, chest pains, sweating, cough with green or bloody mucus, increased pulse, and bluish colored lips or nails because of lack of oxygen. Other pneumonia symptoms include shortness of breath and sharp pains in the chest when you take a deep breath. Sometimes in elderly adults, the only feeling of pneumonia is a pain in the abdomen. When a bacterial infection is superimposed on the flu, symptoms may initially improve only to worsen with higher fevers, increased coughing, and the development of a greenish tinge to sputum.

(For more information, see WebMD's Flu in Older Adults.)

If there is a persistent cough or fever or if shortness of breath or chest pains occur -- especially if these follow another infection such as the flu -- you should contact your doctor. Tests, including a chest X-ray and sputum examination, can help the doctor make the pneumonia diagnosis. While antibiotics can treat bacterial pneumonia, antibiotics cannot treat viral pneumonia.

WebMD Medical Reference

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